WARF: P97166US

Variable Valve Timing Actuator


Frank Fronczak, Scott Adler, Norman Beachley, Ahmad Sabri

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a variable valve timing actuator that will allow for more efficient internal combustion engines.
OVERVIEWValves in automobiles often are operated by cams driven from the engine’s crankshaft. The cams are designed to provide valve behavior characteristics that result in desired engine economy and performance. Valve timing, duration and lift are the three primary characteristics that define valve behavior; valve duration varies directly with engine speed while valve timing and lift tend to stay constant regardless of engine speed. For optimal engine performance, these valve characteristics change between low and high engine speeds and loading; thus, varying the relationship between the crankshaft and camshaft may allow gains in performance at one speed and load, but generally lead to decreased economy at another speed and load.

Auto manufacturers have expressed interest in developing means for adapting valve behavior to allow for changes in a vehicles economy and performance. Attempts have been made to resolve the problems associated with valve behavior including incorporating valve timing changes or camless designs to allow the engine valves to open and close at different times with respect to the crankshaft position. Unfortunately, neither approach has seen great success. A new method of valve actuation is needed.
THE INVENTIONUW–Madison researchers have developed a valve actuator that allows engine valves to be variably and individually controlled without the use of a camshaft. The actuator utilizes energy regeneration so that energy delivered to a valve while it is accelerating is recovered while it is decelerating. The variable valve timing actuator comprises a valve, a spring charger assembly, at least one spring and at least one latch.

The valves are held stationary by a latch which is disengaged when the valve is to begin opening or closing. The latch allows the valve to automatically lock in its open or closed position without the need for a control input; also, no energy is required to hold the valves in a given position. The springs impose an opening force on the valve and once the valve is open, the opposing springs impose a closing force on the valve. Thus, the motion of the valve through a complete cycle may be affected by simply altering the state of the latches, which allows the springs to drive the valve towards an open or closed position.
  • Valve actuators for use in automobiles, particularly those which are actuated hydraulically or electrically without the use of cams
  • More efficient internal combustion engines
  • Improves fuel economy
  • Reduces harmful emissions
  • Low energy requirement for the system
  • Opening and closing times of the valve can be independently varied
For More Information About the Inventors
Contact Information
For current licensing status, please contact Emily Bauer at or 608-960-9842.
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